Hydrogen ions and an accompanying anion are produced as cells enlarge to reestablish their volume. As cells shrink to control their volume, hydioxyl is produced. The formation of hydrogen ions and hydroxyl correlate with initial shifts in cell water and net cation transport. BIBLIOGRAPHIC REFERENCES: Kregenow, F.M.: Cell Volume Control in Water Relations in Membrane Transport in Plants and Animals, eds. A.M. Jungreis, T.K. Hodges, A. Kleinzeller, and S.G. Schultz, Academic Press, New York, 1977, pp. 291-302. Kregenow, F.M.: Transport in avian erythrocytes in Transport in Red Cells. ed. Clive Ellory, Academic Press, New York, 1977, pp. 383-426.